As is known, certificates are being widely used in almost all fields of electronic commerce (e-commerce), not only in Internet shopping but also in online banking, mobile stock trading, and the Internet issuance of public documents.
Such certificates are online forms of identification that are necessary to validate a person's identity so as to allow him or her to conduct convenient Internet transactions, but they are vulnerable in terms of security because certificate files and passwords may be obtained through hacking.
Furthermore, since conventional methods have a problem with the validation of identities, a scheme using bio information is being pursued. Biometric technology has attracted attention as user authentication technology that provides convenience and safety. It was selected as one of the “10 promising technologies for the 21st century” by U.S. MIT, Gartner Group.
With regard to biometric technology, iris recognition technology is the most secure technology among currently implemented biometric technologies, since the probability of one human iris having the same pattern as another is approximately one in six billion. Furthermore, currently, in the U.S., Japan, Great Britain and Germany, identification based on iris recognition is being used as identification means.
In general, a lighting IR LED (infrared LED) is used for iris recognition. The radiation angle (lighting angle) of the lighting IR LED is determined to be twice an angle that is a half of the maximum value of emitted light.
An example of such a radiation angle is as illustrated in FIG. 10. In this case, the radiation angle (lighting angle) is about 125 degrees.
Furthermore, an iris recognition camera lens has a specific field of vision or field of view, and an image within the angular range may be formed on a sensor. It is represented using angles in terms of the specification.
The field of view of a lens may have a variety of combinations depending on the distance between the lens and the iris, the resolution (or the number of pixels) of an image sensor that validates an identity based on an iris image, the performance of a device that is used to validate an identity based on an image, and the structure of a program that is used to perform processing.
For example, when the distance between a lens and an eye is set to a short distance of 5 to 15 cm and an identity is validated based on an iris image using a typical signal processing device having a speed of hundreds of MHz, it is determined that it is sufficient if an image sensor has a resolution of about 640×480 pixels.
In this case, the field of view of the lens is preferably about two or three times the size of the pupil, and about 15 degrees are appropriate.
The range of lighting is preferably wider than the field of view of the lens, in which case the uniformity of the brightness of lighting should be at a level at which image quality that enables an iris image to be desirably processed can be guaranteed. That is, at least 70˜80% is preferable.
The uniformity of brightness may be determined using various methods. In accordance with the simplest of these methods, the relative uniformities of brightness may be compared based an the brightness_maximum value/the brightness_minimum value.
Furthermore, to achieve effective lighting, it is preferred that a lighting range be somewhat wider than the field of view of a lens, that is, by 20˜50%.
That is, when a lighting range is excessively narrow, a variety of additional means are required to achieve the uniformity of brightness in light of the radiation characteristics of a lighting IR LED. In contrast, when a lighting range is wide, relatively strong lighting is required, and thus there arise the disadvantage of power consumption increasing and the disadvantage of the number of lighting components increasing. Since the brightness of lighting is inversely proportional to the square of a lighting area, an amount of light four times the initial amount of light is required to achieve the same brightness when a lighting range is doubled.
As illustrated in FIG. 7, when a lighting IR LED 2 is vertically disposed within a guide 3, a large amount of light is required because a radiation angle (lighting angle) should be widened to irradiate an area around the iris with an appropriate amount of light so as to capture the iris of an eye that is located away from the lens 1 by a specific distance, with the result that the power consumed by the lighting IR LED 2 increases.
Additionally, there are the disadvantage of the lighting IR LED 2 functioning as a conductor that transmits external static electricity to internal mechanical devices (not shown), and the disadvantage of the uniformity of brightness around the iris being deteriorated when the lighting IR LED 2 is used or short-distance lighting.
When a lighting IR LED 2 is inclined and then disposed in a guide as illustrated in FIGS. 8 and 9, there are disadvantages in that an additional support (not shown) is required to, upon installing the lighting IR LED 2 in the guide 3, determine an arbitrary radiation angle (lighting angle) and keep the angle constant, in that there is difficulty with assembly, and in that quality control is extremely difficult upon mass production because it is not easy to determine a predetermined angle with an unaided eye after assembly has been finished.
In addition, since the lighting IR LED 2 is inclined and then disposed within the guide 3, an unnecessary space is formed in the hole of the guide 3 that guides the lighting IR LED 2, thereby causing the disadvantage of supporting force being weakened, the appearance thereof being undesirable, and the size thereof increasing.
Furthermore, in this method of inclining and disposing the lighting IR LED 2, the lighting IR LED 2 is exposed directly to the outside in the same manner as shown in FIG. 7, and thus there are the disadvantage of being weak to external static electricity and the disadvantage of the uniformity of brightness around the iris being poor.
While the scheme of FIG. 9 can improve the uniformity of brightness around the iris using a prism 4 with planar top and bottom surfaces, compared to the scheme of FIG. 8, it still has the disadvantages of the scheme of FIG. 8.
Since the lighting IR LED 2 consumes a specific amount of power to achieve a predetermined light output and thus generates heat upon operation, it is disposed in the metallic guide 3 in order to achieve heat dissipation effects.
In this case, static electricity of thousands of volts is discharged from a human body or air via the metallic guide 3 and internal circuits, and thus erroneous operation of the circuits may occur.
Therefore, a static electricity absorption element is generally used as a static electricity prevention means. The use of the static electricity absorption element is a factor resulting in an increase in cost. Furthermore, since some countermeasure other than a simple static electricity absorption element is required as the prevention means, there is a disadvantage in that the configuration of a camera module that is used to capture the iris is complicated.